Surgical devices are used in various open, endoscopic, and laparoscopic surgeries to seal and/or transect tissue volumes and blood vessels. Devices used for sealing generally include jaws for grasping tissue therebetween and a cutting mechanism that is advanced through the grasped tissue to transect it. In some instances the devices can also be used to seal tissue volumes and blood vessels being transected, for instance by applying electrical energy to the grasped tissue to seal it before tissue transection is completed. For example, various mono-polar and bi-polar radio frequency (RF) surgical instruments and surgical techniques have been developed for sealing tissue volumes and blood vessels. Electrodes can be disposed on a face of one or both of the jaws and can apply energy to the grasped tissue to promote hemostasis.
One issue that can plague electrosurgical cutting devices is that tissue volumes and blood vessels being sealed may become damaged. When operating a tissue compression device, an amount of compression applied by the jaws to the tissue affects hemostasis. By increasing the amount of compression applied to the target tissue, the flow of blood can be limited, which can decrease the time necessary to achieve hemostasis. However, applying too much compression to manipulate tissue without sealing the tissue can result in damage to the tissue. The tissue is grasped and sealed by jaws of a surgical device having an electrode disposed in one or both of the jaws. Because an optimal amount of force depends on various factors, including the type and thickness of tissue disposed between the jaws, overcompression may result. Overcompression can make it difficult to apply resistive heating to tissue using an RF tissue sealing device and may result in a greater than desired contact area of the jaws with the grasped tissue. This increased contact area may cause undesired burning or charring of the tissue. Additionally, the inability to electrically isolate the electrode from the remaining jaw results in unwanted erosion of insulator material on the contact surface of the opposite jaw or an interruption of the electrical energy to the tissue. Higher compression settings move the jaws closer towards one another, causing parts of the electrode to directly contact the surface of the opposite jaw, possibly eroding the insulator material located thereon.
Accordingly, there remains a need for improved devices and methods that consistently and precisely set the gap between the jaws of the surgical device so as to avoid damage to the device, to the tissues being grasped and sealed when the device is in use, and ensure that the electrodes do not make contact with each other and short the device.